Repeating components in Wordpress Gutenberg

gutenberg-module.js

```
  edit: repeater({
      editing: true,
      renderComponent: ({ attributes: { name }, setAttributes }) => 
        <MyComponent
          name={
            <PlainText
              value={ name }
              placeholder={'Name'}
              onChange={ value => setAttributes( { name: value } ) }
            />
          }
        />
  }),
  save: repeater({
      renderComponent: ({ attributes: { name } }) => <MyComponent name={name} />
  })
```

repeater.js

const repeater = ({
  attribute: key = 'data',
  renderComponent,
  renderContainer = (props) => <div {...props} />,
  editing = false,
}) => ({ attributes, setAttributes }) => {
  // WP doesn't support array of objects :)
  let thisAttribute;
  try  {
    const parsed = JSON.parse(attributes[key]);
    thisAttribute = Array.isArray(parsed) ? parsed : [{}];
  } catch (e) {
    thisAttribute = [{}];
  }

  return renderContainer({
    children: <React.Fragment>
      {
        thisAttribute.map((item, i) => {
          const thisIndex = i;
          const setIndexedAttribute = (obj) => {
            Object.keys(obj).map(k => thisAttribute[thisIndex][k] = obj[k]);
            setAttributes({
              [key]: JSON.stringify(thisAttribute)
            });;
          }
          return renderComponent({
            index: i,
            attributes: thisAttribute[thisIndex],
            setAttributes: setIndexedAttribute
          })
        })
            }
            {
        editing &&
        <div>
          <button onClick={() => {
            thisAttribute.length && thisAttribute.pop();
            setAttributes({
              [key]: JSON.stringify(thisAttribute)
            });
          }}>One less</button>
          <button onClick={() => {
            thisAttribute.push({});
            setAttributes({
              [key]: JSON.stringify(thisAttribute)
            });
          }}>One more</button>
        </div>
      }
    </React.Fragment>
  })
}